and frequently do but the procedures are well established.
Recreational Pony Bottles, completely unnecessary? Why or why not?
- Thread starter Hartattack
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How will that help this discussion? Why can't you tell me in a sentence or so why it has to take 9 minutes for an OOA diver to go to the surface from 80 feet on an NDL dive?
No authority required, the procedures are established by those that use them. A stage is turned off because you know when it will be required within the dive plan, with a pony it is best to have it available immediately in an emergency and you don't really want to have to faff about turning it on. Others may have adopted other procedures but those I know tend to adopt these.
So the established procedure was established by those who agree with it, and if someone disagrees, they can say "Hey! You can't argue with it! It's established!"
In my example, the diver started with the stage, so it was turned on right away and then later turned off at a certain point according to plan. That's how most stages are used.
It takes about a quarter turn of a knob to get all the gas flowing.
OP
It is important to remember that an ascent speed of 3m/ 10ft per minute during the MG calculations is an assumption based on a relatively slow but foreseeable ascent rate and likely provides a slight cushion of safety which should be maintained until divers are sufficiently experienced to adjust based upon real life experience. (This discussion was started because folks on SB were recommending Pony bottles to new open water divers in another thread) Divers should attempt to maintain a controlled ascent of between 6 and 9 meters (20 to 30 feet) per minute and preferably follow Minimum Deco ascent profile. Likewise, a 0.75 cuft per min SCR is an approximation based on the outcome of an average diver in most situations. Divers should calculate their personal SCR rates during various dives as well as during ascents while remembering that stress during an emergency will invariably affect the amount of gas needed (Kjoller et al., 2019).
Kjoller, J., Czerny, D., & Jablonski, J. (2019). Minimum Gas . In Fundamentals of Better Diving (pp. 78–85). essay, Global Underwater Explorers .
This does not answer my question. I asked you WHY divers need to follow a minimum deco ascent profile during an OOA event. What is the reason for it? Please cite references to research indicating that it is necessary to do so in an emergency, not just the opinion of the guy who made it up.
OP
I'm a little confused with your question, would you like to go over proven gas laws and theories? The thought process is, that once the OOG diver has a working regulator in their mouth, the emergency is over but the dive must end. Thus, the divers go up on a slightly conservative ascent profile to factor in heavy SCR's and mitigate panic while also giving their bodies time to off-gas.
However, we normally do a "minimum decompression ascent" for rec dives.
E.g. Divide the depth by two. In the first half of the ascent, the travel rate is 9m/30ft per minute, and in the second half , the rate slows down to 3m/10ft per minute.
The second phase of the minimum decompression ascent, conducted at 3m /10ft per minute is usually performed as a series of punctuated stops maintaining overall ascent rates.
CT-Rich
Contributor
I believe this is his concern…
OP
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